Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;

int main(){
	// sengen
	int h,w;
	// nyuryoku
	cin >> h >> w;
	char s[h][w];
	int count = 0;
	int dist[h][w];
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			cin >> s[i][j];
			dist[i][j] = -1;
			if(s[i][j] == '.'){
				count++;
			}
		}
	}
	int dx[4] = {-1,1,0,0};
	int dy[4] = {0,0,-1,1};
	// keisan
	queue<pair<int,int>> que;
	que.emplace(0,0);
	dist[0][0] = 1;
	while(!que.empty()){
		pair<int,int> now = que.front();
		que.pop();
		for(int i=0;i<4;i++){
			int nx = now.first + dx[i];
			int ny = now.second + dy[i];
			if(nx<0 || ny<0 || nx>h-1 || ny>w-1) continue;
			if(s[nx][ny] == '#') continue;
			if(dist[nx][ny] == -1){
				dist[nx][ny] = dist[now.first][now.second] +1;
				que.emplace(nx,ny);
			}
		}
	}
	// syutsuryoku
	if(dist[h-1][w-1] == -1){
		cout << "-1";
	}else{
		cout << count - dist[h-1][w-1];
	}
}